(1) Field of the Invention
The present invention relates to an image storing device which can be suitably applied to an electronic filing system, and in particularly, to the image storing system capable of storing a plurality of encoded, compressed images and displaying objective decoded, expanded images.
(2) Description of the Related Art
According to a recent electronic filing system, it has become possible to store an encoded and compressed data instead of an original image data. By storing the encoded, compressed data, the memory capacity of the filing system can be enhanced. Then, the file data is decoded and expanded into the original image data, and outputted to a printer; otherwise it is displayed on a Cathode-Ray Tube (CRT) display unit or a liquid crystal display unit. When a massive amount of the encoded, compressed data is stored, it takes time to retrieve the objective data. Accordingly, an improved method of successively retrieving and displaying the objective data at a high speed has been longed for.
Generally, the resolution of a display unit, such as a CRT, is lower than the resolution of a printer. Accordingly, to realize a high-speed output onto the display unit, reduction images are stored for the high-speed display besides storing a usual image for a printer.
An image storing device which is applied to the conventional electronic filing system will be described.
FIG. 1 shows the configuration of the image storing device including an image memory 11 for storing an original image data scanned with an optical scanner, an encoding and compressing unit 12 for encoding the original image data and compressing it, an encoded data memory 13 for storing the encoded, compressed data, a decoding and expanding unit 14 for decoding and expanding the encoded, compressed data, an image data delivery unit 15 for delivering the original image data from the image memory 11 to the encoding and compressing unit 12, an encoded data delivery unit 16 for delivering the encoded, compressed data from the encoding and compressing unit 12 to the encoded data memory 13 and for delivering the encoded, compressed data from the encoded data memory 13 to the decoding and expanding unit 14, an output unit 17 comprised of the printer, liquid cathode-ray tube, liquid crystal display, or the like which is dedicated to output the decoded, expanded image data derived from the decoding and expanding unit 14, an image reduction unit 18 for reducing the original image data from the image memory 11, and a reduced, encoded data memory 19 for storing the encoded (compressed), reduced data.
The storing of an image data (storing the image data which can be accessed to be reproduced) and the high-speed output to the display unit will be described.
An image data will be stored.
(1) Receiving the image data from the image memory 11, the image data delivery unit 15 delivers it to the encoding and compressing unit 12. PA0 (2) The encoding and compressing unit 12 encodes and compresses the image data simultaneously. PA0 (3) The encoded data delivery unit 16 delivers the encoded, compressed data from the encoding and compressing unit 12 to the encoded data memory 13. The encoded data memory 13 stores the encoded, compressed data. PA0 (4) According to a resolution of the display unit, the image reduction unit 18 reduces the original image data from the image memory 11. As an exemplary means, the original image data is subdivided into 9 (3.times.3) subregions in advance and the subregion positioning at the bottom row and the left column will be selected. Otherwise, the nine subregions will be averaged into 1.times.1 subregion. Accordingly, the original image data will be reduced into one-third by size. PA0 (5) The image data delivery unit 15 delivers the reduced image data from the image reduction unit 18 to the encoding and compressing unit 12. PA0 (6) The encoding and compressing unit 12 encodes the reduced image data from the image data delivery unit 15 and compresses it. PA0 (7) The encoded data delivery unit 16 delivers the encoded, compressed data from the encoding and compressing unit 12 to the reduced, encoded data memory 19; and the reduced, encoded data memory 19 stores it. PA0 (8) The encoded data delivery unit 16 retrieves the encoded (compressed), reduced data from the reduced, encoded data memory 19, and delivers it to the decoding and expanding unit 14. PA0 (9) The decoding and expanding unit 14 decodes and expands the encoded (compressed), reduced data into the original reduced image data. Since the data amount of the reduced data is relatively small, the encoded (compressed), reduced data will be decoded and expanded at a high speed. PA0 (10) The image data delivery unit 15 delivers the decoded, reduced image data from the decoding and expanding unit 14 to the output unit 17. PA0 (11) The output unit 17 displays the decoded, reduced image data on the CRT or the like at a high speed.
A reduced image data will be stored.
An encoded, compressed data will be outputted.
When outputting the encoded, compressed data which is not reduced, the encoded data delivery unit 16 retrieves the encoded, compressed data from the encoded data memory 13, and delivers it to the decoding and expanding unit 14. The decoding and expanding unit 14 decodes and expands the encoded, compressed data, and provides the decoded data to the image data delivery unit 15. The decoded data from the image data delivery unit 15 is printed by the printer in high quality.
A reduced image will be displayed at a high speed.
Thus, according to the conventional image storing device, in order to display successive images at a high speed for searching, the image storing device reduces the original images in advance, encodes and compresses the reduced images, then stores the encoded, compressed data of the reduced images besides storing the encoded, compressed data of the original images. Therefore, when a high-speed display is desired, the encoded, compressed data of the reduced images is decoded and expanded.
Thus, by storing the encoded, compressed data of the reduced images, the display speed can be enhanced; however, the total data amount is increased thereby. Additionally, the data amount for an image data is great even for a reduced image.
When the original document includes characters, it is preferable to reduce the document both in the horizontal and vertical directions at the same reduction rate so that the characters are easily recognized. When the original document includes a diagram, on the other hand, it is preferable to enhance the display speed by reducing it only in the vertical direction or reducing only a left half of the original document.
Furthermore, when the original document includes characters which would be hardly recognizable if reduced at a large reduction rate, a small reduction rate should be applied. Thus, it is desirable to change the reduction rate freely.